Engine/Transmission (1998.5 - 2002) Problems installing my EGT guage

[Renoram]

I started installing my Isspro EV EGT pre-turbo gauge today & had 2 problems. '99 Ram QC, automatic, 4x4



First I drilled & tapped the 1/4" npt hole. That went fine. When I went to install the thermocouple, I found that it bottomed out on the bottom of manifold way before I could even start threading it in. I followed the Isspro website instructions- 3/4" up from the flange , centered on the aft exhaust port. My thermocouple is 2 1/4" long from the bottom of the threaded adapter that screws into the manifold. Just to get the probe to center in the exhaust port, I went to Home depot & bought the shortest 1/4" npt nipple & female adapter sleeve. That put me about half way in the port. It seems like the thermocouple should be around 1 1/2" long instead of the 2 1/4" to center in the port. Does anyone have a thermocouple out to measure? Any help would be appreciated.



Next I ran the cable to the cab & hooked up to Power supply & gauge. I started it up & no indication (needle movement) at all. I metered 12v to power supply. I may have crimped insulation on the ground. I will check tomorrow- it was getting dark & cold. I gave up for today. Any other ideas. Thanks.

 

[KLockliear]

If I remember correctly, the Isspro thermocouples have a 1/4" NPT bottom thread, which has a hex on it to thread it in, but there is another hex above that one of a smaller size. If you loosen this one up, it releases the pressure on a compression ferrule inside, and you can slide the thermocouple up.

 

[Sticks]

Originally posted by KLockliear

If I remember correctly, the Isspro thermocouples have a 1/4" NPT bottom thread, which has a hex on it to thread it in, but there is another hex above that one of a smaller size. If you loosen this one up, it releases the pressure on a compression ferrule inside, and you can slide the thermocouple up.

I just installed the same gauge a few weeks ago. Ditto above.

 

[Renoram]

Thanks guys. One more question. What is the correct position of the thermocouple in the exhaust passage.



Should the end of tip of the thermocouple be in the middle of the exhaust passage?



I'm going to try & get this to work today.

 

[kboettcher]

Yes... . just get it so the tip is in the middle of the passageway... ... only the tip of a thermocouple does the measuring.

 

[KLockliear]

Once that ferrule fitting is loose, you can move the probe up and down with the main fitting tight in the manifold. Go down until it bottoms, then pull it back about 1/2" and tighten it up.

 

[Renoram]

I just got done messing with the EGT guage installation. Thanks for the help on the positioning of the probe. You guys are great!



The gauge is still dead. I checked all the connections again- red to red, yel. to yel. , good power to red on ignition, good ground to black, reset plug from box to gauge, checked wiring at gauge for wires touching/ or disconnected. No help- still dead. I hooked up lighting circuit, thats great.



Any more help anyone can lend?



Getting desperate. Maybe, have to call Diesel Injection Service tomorrow.

 

[Sageair]

You did try starting the truck I presume?

 

[Wiredawg]

Did you remove jumper...

I have DiPricol Guage and it came with a wire attached to the two leads going into the gauge... . this needs to be removed. The guage shouldn't be powered by 12 VDC, only the lights. The gauges is actually powered from slight voltages induced between the disimiler metals. That's why it reads temp when ign switch is off.



Wiredawg

 

[Renoram]

Interesting thing. I left everything hooked up after the unsucessful test drive. Later this evening I had to run a 15 minute errand. It did not work on the way to the errand. When I was returning home, it started working. I'll check it tomorrow again.



This Isspro Egt indicator uses 12vdc to power a "signal amplifier box". I even verified on my instruction sheet wiring diagram. It also has an independant wiring circuit for the lighting which uses 12vdc, as with my boost & transmission temp gauges. I know what you're saying about EGT thermocouples- I work on jets for an airline- mechanical, avionic, electrical & instrument systems for about 38 years. Jet engines have used them practically ever since they were invented!



I guess it was like we call them in the aircraft maintenance business- an anomolly. Or I have a cracked circuit board or solder in the box (dont know what it looks like inside) or something intermittent. Only time will tell!

 

[Renoram]

So far so good! I drove the Ram aroud a bit today & the EGT didnt miss a lick.



I also got my transmission temp guage going today. I lost 3 qts of fluid changing the cooler line.



Now I have everything going- EGT, boost, transmission temp & lighting.



Thanks to all that helped- even the humor from Winnemuca!